The aim of this paper is to obtain coefficient estimates of the integral operator of the form: and
using the relationship between starlike and convex functions and give its implication to disease control. Also, we obtain the growth and distortion theorems for the operator.
Let A denote the class of normalized univalent functions of the form
![]() | (1) |
which are analytic in the unit disc with
In the class of analytic functions in (1) above, the coefficients is the quotient of the nth derivative of the function been expressed in Taylor series expansion and n!. Derivatives, whether partial or total, describe the slope of a function which is the steepness of a line. It is a known fact that the larger the slope, the steeper the line and vice versa. The coefficients
play prominent role in analytic functions. Thus, in applying analytic functions to any area of life, one needs to consider it's coefficient bounds. The author in 6 stated that starlike and convex functions, which are aspect of analytic functions have its applications in human physiology, physical and natural phenomenon. Analytic functions can also be applied to curtailing the spread of any disease, or its occurrence. Here, we think of applying analytic functions to prevention of population of carrier of disease organism from being transformed to infectious population and thereby preventing them from being transformed to disease population. In 10, major categories of infectious agents and common vectors and vehicles of disease were given while Harvard health publishing in 9, gave some ways of preventing infections, World health Organization in 11 stated that there is an urgent need to re-establish basic infection control measures and in 12 gave measures of controlling the spread of infectious diseases, which is still very relevant today. Different authors have derived several differential operators. Author in 4, derived a new multiplier differential operator, in an attempt to get a class of analytic functions with finer coefficients bounds which give a better result in an application mentioned above.
For the function f of the form (1) in A, the following results are well known: f is said to be starlike respectively convex if and only if
![]() |
And
![]() |
Swamy 7, introduced a multiplier differential operator of the form defined by:
![]() |
which is analytic and univalent in the unit disk. For details see 7.
Author in 5 defined a linear operator by:
![]() | (2) |
and the class by:
![]() |
Where
![]() |
And
![]() | (3) |
Now, let
![]() | (4) |
We define by:
![]() | (5) |
and the class by:
![]() | (6) |
Where
Furthermore, let
![]() |
and
![]() |
we define the convolution of and
by:
![]() | (7) |
In this paper, we obtain the coefficients bound for the class and apply it to disease control measure.
Lemma 3: Let be as in (3). Then
is in the class
if and only if
![]() |
Now we state and prove the main results of this paper.
Theorem 1: Let be as in (5). Then
belong to the class
if
![]() |
Proof: Given that
![]() |
And
![]() |
with simple calculation, we have
![]() |
Where
![]() |
For we have
![]() |
This is bounded by if
![]() |
Fixing the value of x and restructuring, we have the result.
Remark: The above theorem shows the relationship between the convexity of the integral operator in (5) and the starlikeness of the differential operator in (4).
Corollary 1: Let be as defined in (5) and
belongs to the class
Also, let
belongs to the class
as given in lemma 1. Then
Proof: Let be as defined in (5) and
belongs to the class
From theorem 1, we have for
![]() |
For
This proves the result.
Corollary 2: Let belongs to the class
Then
![]() |
and
Corollary 3: Let belongs to the class
. Then
![]() |
Corollary 4: Let belongs to the class
Then
![]() |
Corollary 5: Let belongs to the class
Then
![]() |
Corollary 6: Let belongs to the class
Then
Corollary 7: Let belongs to the class
Then
Theorem 2: Let be as in (5) and
Then
(z) belong to the class
if
![]() |
Where and
Proof: Let
belong to the class
Then from Theorem 1, and for real value of z we have:
![]() |
And
![]() |
We need to find the smallest such that
![]() | (8) |
By Cauchy Schwartz inequality, we have:
![]() | (9) |
Thus, it suffices to show that:
![]() |
From where we have:
![]() |
And by (10), we have:
![]() |
And by simple simplification, with and
we have:
![]() | (10) |
This proves the result.
Corollary 8: Let be as in (5) and
belong to the class
Then
![]() |
and
Where is as defined in (10) and
respectively.
Corollary 9: Let be as in (5) and
Then
![]() |
Where is as defined in (10) and
respectively.
Corollary 10: Let be as in (5) and
Then
![]() |
Where is as defined in (10) and
respectively.
In what follows, we show that the class is close under convex combination.
Theorem 3: Let be as in (5) and
Then given by
![]() |
belongs to the class Where
Proof: Let and
belong to the class
Then we have
![]() | (11) |
And respectively
![]() | (12) |
adding (11) and (12) gives
![]() |
This proves the result.
Now, we establish two of the fundamental theorems about univalent functions in relation to function in the subclass the growth and distortion theorems, which provide bounds on
and
respectively. Theorems (4) and (5) below are the growth and distortion theorems respectively.
Theorem 4: Let belong to the class
Then
![]() |
Proof: For the function
![]() |
Similarly,
![]() |
Fixing the value of for the function in
and rearranging gives the result.
Theorem 5: Let belong to the class
Then
![]() |
Proof: The proof follows from theorem 4.
In this article, we take the coefficients of the analytic functions in the above theorems as the size of some dynamic parameters, which could be infectious agents, such as viruses, bacteria, fungi, protozoa, and helminthes, that need to be curtailed to achieve the above aim and the and
are infection control measures. Thus, to achieve reduction in the infectious agents, we need to reduce the slope of the class of functions
![]() |
which is the coefficients It is noted from the above that the higher the control measures, the smaller the coefficient bounds. And that the coefficient bounds in the theorems above is of less magnitude than those obtained in the previous literature, thus it will yield a better result in the prevention we aimed at.
[1] | N. E. Cho and H. M. Srivastava, Argument estimates of certain analytic functions defined by a class of multiplier transformations, Math. Comput. Modeling, 37(1-2) (2003), 39-49. | ||
In article | View Article | ||
[2] | N. E. Cho and T. H. Kim, Multiplier transformations and strongly Close-to-Convex functions, Bull. Korean Math. Soc., 40(3) (2003), 399-410. | ||
In article | View Article | ||
[3] | D.O. Makinde and A.T. Oladipo, Some properties of certain subclasses of univalent integral operators, Scientia Magna 9(1)(2013), 80-88. | ||
In article | |||
[4] | D.O. Makinde, A new multiplier differential operator, Advances in Mathematics: Scientific Journal, 7(2) (2018), 109-114. | ||
In article | |||
[5] | D.O. Makinde et-al, A generalized multiplier transform on a univalent integral operator, Journal of Contemporary Applied Mathematics 9(1) (2019), 31-38. | ||
In article | |||
[6] | D.O. Makinde, Studies on the starlikeness and convexity properties of subclasses of analytic and univalent functions, A Dissertation Submitted to The Department of Mathematics, Faculty Of Science, University Of Ilorin, In Partial Fulfillment of The Requirements For The Degree Of Doctor Of Philosophy In Mathematics (Ph.D) University of Ilorin, Ilorin, Nigeria 2010. | ||
In article | |||
[7] | S. R. Swamy, Inclusion Properties of Certain Subclasses of Analytic Functions, International Mathematical Forum, Vol. 7, no. 36,(2012) 1751-1760. | ||
In article | |||
[8] | H. Silverman, Univalent functions with negative coefficients, Proceedings of the American Mathematical Society, Vol 51, Number 1, (1975), 109-115. | ||
In article | View Article | ||
[9] | https://www.health.harvard.edu/staying-healthy/how-to-prevent-infections. | ||
In article | |||
[10] | https://www.ncbi.nlm.nih.gov/books/NBK209710/. | ||
In article | |||
[11] | https://www.who.int/healthsystems/topics/health-law/chapter10.pdf. | ||
In article | |||
[12] | http://www.euro.who.int/data=assets=pdff ile=0013=102316=e79822:pdf. | ||
In article | |||
Published with license by Science and Education Publishing, Copyright © 2019 Deborah Olufunmilayo Makinde
This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit
http://creativecommons.org/licenses/by/4.0/
[1] | N. E. Cho and H. M. Srivastava, Argument estimates of certain analytic functions defined by a class of multiplier transformations, Math. Comput. Modeling, 37(1-2) (2003), 39-49. | ||
In article | View Article | ||
[2] | N. E. Cho and T. H. Kim, Multiplier transformations and strongly Close-to-Convex functions, Bull. Korean Math. Soc., 40(3) (2003), 399-410. | ||
In article | View Article | ||
[3] | D.O. Makinde and A.T. Oladipo, Some properties of certain subclasses of univalent integral operators, Scientia Magna 9(1)(2013), 80-88. | ||
In article | |||
[4] | D.O. Makinde, A new multiplier differential operator, Advances in Mathematics: Scientific Journal, 7(2) (2018), 109-114. | ||
In article | |||
[5] | D.O. Makinde et-al, A generalized multiplier transform on a univalent integral operator, Journal of Contemporary Applied Mathematics 9(1) (2019), 31-38. | ||
In article | |||
[6] | D.O. Makinde, Studies on the starlikeness and convexity properties of subclasses of analytic and univalent functions, A Dissertation Submitted to The Department of Mathematics, Faculty Of Science, University Of Ilorin, In Partial Fulfillment of The Requirements For The Degree Of Doctor Of Philosophy In Mathematics (Ph.D) University of Ilorin, Ilorin, Nigeria 2010. | ||
In article | |||
[7] | S. R. Swamy, Inclusion Properties of Certain Subclasses of Analytic Functions, International Mathematical Forum, Vol. 7, no. 36,(2012) 1751-1760. | ||
In article | |||
[8] | H. Silverman, Univalent functions with negative coefficients, Proceedings of the American Mathematical Society, Vol 51, Number 1, (1975), 109-115. | ||
In article | View Article | ||
[9] | https://www.health.harvard.edu/staying-healthy/how-to-prevent-infections. | ||
In article | |||
[10] | https://www.ncbi.nlm.nih.gov/books/NBK209710/. | ||
In article | |||
[11] | https://www.who.int/healthsystems/topics/health-law/chapter10.pdf. | ||
In article | |||
[12] | http://www.euro.who.int/data=assets=pdff ile=0013=102316=e79822:pdf. | ||
In article | |||